System Memory; Overview; Memory Configurations - Asus M4A78-HTPC User Manual

1.7

System memory

1.7.1

Overview

The motherboard comes with two Double Data Rate 2 (DDR2) Dual Inline Memory Modules
(DIMM) sockets. A DDR2 module has the same physical dimensions as a DDR DIMM but
has a 240-pin footprint compared to the 184-pin DDR DIMM. DDR2 DIMMs are notched
differently to prevent installation on a DDR DIMM socket. The figure illustrates the location of
the DDR2 DIMM sockets:
Channel
Channel A
Channel B
1.7.2

Memory configurations

You may install 512MB, 1GB, 2GB and 4GB unbuffered ECC/non-ECC DDR2 DIMMs into the
DIMM sockets.
• You may install varying memory sizes in Channel A and Channel B. The system maps
• Always install DIMMs with the same CAS latency. For optimum compatibility, we
• Due to the memory address limitation on 32-bit Windows OS, when you install 4GB
• This motherboard does not support DIMMs made up of 256 Mb chips or less. (Memory
• The default memory operation frequency is dependent on its SPD. Under the default
• For system stability, use a more efficient memory cooling system to support a full
1-10
Sockets
DIMM_A1 and DIMM_A2
DIMM_B1 and DIMM_B2
the total size of the lower-sized channel for the dual-channel configuration. Any excess
memory from the higher-sized channel is then mapped for single-channel operation.
recommend that you obtain memory modules from the same vendor.
or more memory on the motherboard, the actual usable memory for the OS can be
about 3GB or less. For effective use of memory, we recommend that you install a 64-bit
Windows OS when having 4GB or more memory installed on the motherboard.
chip capacity counts in Megabit, 8 Megabit/Mb=1 Megabyte/MB.)
state, some memory modules for overclocking may operate at a lower frequency than
the vendor-marked value.
memory load (4 DIMMs) or overclocking condition.
ASUS M4A78-HTPC